Relay controller

ABSTRACT

A relay controller for connecting a power source includes at least one relay having at least two contacts. The relay controller includes a processing device operable to selectively switch the relay contacts, and a feedback circuit adapted to identify an actual state of the relay contacts. The processing device is configured to recognize a fault contact condition of a disparity between an expected state of the relay contacts and the actual state of the relay contacts. The processing device is also configured to responsively communicate information relating to the relay fault condition.

FIELD OF THE INVENTION

The present invention relates generally to relay controllers, and moreparticularly to communicating relay controllers.

BACKGROUND OF THE INVENTION

A relay controller circuit may generally include a processing device anda relay having contacts. The contacts are driven by the processingdevice to an open position or a close position, depending on the desiredoutput of the relay. In various applications of the relay controller,the relay may be switched frequently throughout its lifetime. The numberof switches in its lifetime, along with conditions under which the relayis switched, causes the relay contacts to degrade.

The degrading of the relay contacts can cause failures of the relay toswitch when commanded by the processing device. The failure maymomentarily interrupt normal relay switching operation, or may bepermanent. Depending on the degradation of the relay contacts, the relaymay still be able to switch and function in the degraded state. If therelay does not switch, the relay has failed, and will not functionwithout repair or replacement.

SUMMARY OF THE INVENTION

The inventor hereof has succeeded at designing relay controllers andmethods of operation that are capable of communicating a servicerequirement. The communicating of the service requirement can diminishor eliminate system down time and prevent damage to critical componentsby communicating service requirements before a failure of the relay.

According to one aspect of the present invention, a relay controller forswitching a power source includes at least one relay having at least twocontacts, a processing device operable to selectively switch the relaycontacts and a feedback circuit adapted to identify an actual state ofthe relay contacts. The processing device is configured to recognize afault contact condition. The fault contact condition is a disparitybetween an expected state of the relay contacts and the actual state ofthe relay contacts. The processing device is also configured toresponsively communicate information relating to the fault condition.

According to another aspect of the present invention, a method ofoperating a relay controller having at least one relay having at leasttwo contacts includes monitoring an expected state of the relay contactsand an actual state of the relay contacts, upon detection of a faultcontact condition, pulsing the relay until the fault contact conditionis overcome, and communicating information relating to the faultcondition.

According to yet another aspect of the present invention, a relaycontroller for a relay having a first relay contact and a second relaycontact adapted to close to establish an electrical connection betweenthe first and second voltage waveforms and a motor. The relay controlleris further associated with a first electrical circuit having inputconnections adapted for connection to the first and second voltagewaveforms. The first electrical circuit is configured to provide asignal denoting a time when each of the first and second waveforms areeach at a voltage value other than zero volts, and the difference involtage potential between the first alternating-current voltage waveformand the second alternating-current voltage waveform is at or near aminimum value, at which time the relay is initially switched to initiateclosure of the first and second relay contacts. The relay controller isfurther associated with a second electrical circuit having inputconnections with the first and second relay contacts for monitoring therelay contact position, wherein when the relay first and second contactsare closed, the second electrical circuit is configured to provide asignal denoting a time when the relay contacts have closed and opened.The relay controller further includes a microprocessor configured toswitch the relay, causing the opening and closing of first and secondrelay contacts. The microprocessor is configured to monitor the firstand second signals to determine a difference in time between when therelay is initially switched where the difference in voltage potential isat or near a minimum value, and when the first and second relay contactsactually close, where the microprocessor utilizes the time differencevalue in determining a switch initiation time relative to a time wherethe difference in voltage potential is at or near a minimum value, suchthat the first and second relay contacts close when the voltagepotential between the first and second alternating-current voltagewaveforms is at or near a minimum value, to thereby reduce the potentialfor arcing.

Further aspects of the present invention will be in part apparent and inpart pointed out below. It should be understood that various aspects ofthe invention may be implemented individually or in combination with oneanother. It should also be understood that the detailed description anddrawings, while indicating certain exemplary embodiments of theinvention, are intended for purposes of illustration only and should notbe construed as limiting the scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a circuit diagram of a relay controller according to oneembodiment of the present disclosure.

FIG. 2 is a flow chart of one embodiment of a method for controlling theoperation of a relay controller;

FIG. 3 is a flow chart of a second embodiment of a method forcontrolling the operation of a relay controller;

FIG. 4A is a voltage waveform illustrating a contact closure not at awaveform-crossing.

FIG. 4B is a voltage waveform illustrating a contact closure at a crosspoint of two waveforms.

FIG. 5 is a flow chart of a third embodiment of a method for controllinga relay controller that includes an offset;

FIG. 6 is a voltage waveform illustrating a contact closure at a crosspoint of two waveforms of a 208 AC voltage source used in aY-configuration with respect to ground.

FIG. 7 is a block representation of a second embodiment of a relaycontroller circuit;

FIG. 8 is a circuit diagram of one embodiment of a feedback circuit fora relay controller shown in FIG. 7.

FIG. 9 is a graph exemplifying relay operation over time using a relaycontroller and method of the present disclosure.

Like reference symbols indicate like elements or features throughout thedrawings.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

The following description of exemplary embodiments is merely exemplaryin nature and is in no way intended to limit the scope of the presentinvention, its applications, or uses.

One embodiment of a relay controller according to the principles of thepresent specification is illustrated in FIG. 1 and is indicatedgenerally by reference numeral 100. The relay controller 100 includes atleast one relay 102 having at least two contacts 104, 106, a processingdevice 108, and a feedback circuit 110. The processing device 108 isoperable to selectively switch the relay contacts 104, 106. The feedbackcircuit 110 is adapted to identify the actual state of the relaycontacts. The processing device is configured to recognize a relay faultor un-expected state of the contacts, and to responsively communicate asignal indicative of the fault or un-expected contact state.

A relay fault condition may be a disparity between an expected state ofthe relay contacts and the actual state of the relay contacts. The relaycontroller is operable to selectively switch the relay contacts betweenan open position and a closed position. The closed position creates anelectrical continuity between the contacts, and the open positioncreates an electrical discontinuity between the contacts. The expectedstate of the contacts is that state commanded by the processing device,and the actual state of the contacts is the actual open or closedposition of the contacts. For example, the relay fault condition may bea contact weld condition. The contact weld condition exists when a weldforms between the contacts to inhibit the transition of the contactsfrom the closed position to the open position. In another example, therelay fault condition is a failure of the closed position contacts tocreate electrical continuity between the contacts, due to a highimpedance condition. In other embodiments, different types of faultcontact conditions can exist depending on at least the type of relay andenvironmental conditions of operation of the relay.

To overcome a relay fault condition, the processing device may repeatthe command or activation signal to the relay. The command or activationsignal from the processing device switches the relay to a particularcontact state. For example, upon determining a contact weld condition,the processing device may establish a command or activation signal forclosing the contacts (which signal may be a voltage to the relay)followed by a command or activation signal for opening the contacts(which signal may be an interruption of voltage). If the actual state ofthe contacts does not change from the weld condition in response to thecommand signals, the processing device will detect the continued faultcondition and repeat the “pulse” command to the relay. The relay may be“pulsed” until the fault condition is overcome and the actual state ofthe relay contacts is consistent with the expected state of the relaycontacts. In another example in which the contacts are in the closedposition but do not have electrical continuity between the contacts, theprocessing device may establish a command or activation signal foropening the contacts (which signal may be either an interruption orapplication of voltage to the relay) followed by a command or activationsignal for closing the contacts. If the contacts close and establishelectrical continuity then the fault condition is overcome, and theactual state of the relay contacts is consistent with the expected stateof the relay contacts.

In various embodiments, the processing device is adapted to storeinformation corresponding to a particular fault condition. Theinformation may include pulse characteristics, such as the number ofpulses necessary to overcome the particular fault contact condition, orthe pulse frequency for overcoming the particular fault contactcondition. In some relay controller embodiments, analysis of the faultsand pulse characteristics can be used to predict subsequent failure orultimate failure of the relay. In one embodiment, the analysis comprisescomparing the number of pulses required to overcome a fault conditionwith a predetermined maximum number of allowed pulses stored in theprocessing device. For example, if the number of pulses required toovercome the fault condition is 5 times and the predetermined maximum is6 times, the processing device may responsively predict an imminentfailure. The predetermined maximum can be a fixed or variable valuedepending on a number of factors, including the operating load orcurrent conducted, the type of relay, the number of contacts, othercomponents in the system, etc. For example, empirical testing of aspecific relay may disclose that the specific relay when operated over100,000 times or cycles will most likely not overcome a contact weldfault condition, even after 6 successive pulses. The predeterminedmaximum value may accordingly be set to some number less than 6 times.In other embodiments, the pulse characteristics can be analyzedindependent of a predetermined maximum to form a predicted failure basedsolely on the number of fault occurrences and the number of times therelay has been switched or “cycled”.

The processing device may communicate the type of fault condition, andother information such as a predicted failure point for the relay. Thecommunication may include the number of pulses required to overcome therelay fault condition. The analysis of the fault type, pulsecharacteristics, and number of relay cycles may be used in estimating orpredicting a subsequent or ultimate failure of the relay. Accordingly,the fault information and predicted failure can provide a variety ofdata for the processing device to communicate. Moreover, someapplications in which the relay controller may be employed might demandthat the relay controller communicate a service requirement for a singlefault condition, where the relay is critical to the system. Otherapplications may be much more fault tolerant and can wait until justbefore ultimate failure of the relay to communicate diagnostic orservice information to an interface or display device. Accordingly, therelay controller may be adaptable to different applications with eithercritical or non-critical components.

While FIG. 1 illustrates a single relay 102 having two contacts 104 and106, it should be understood that a different number of contacts ordifferent types of relays can be employed in other embodiments of arelay controller. For example, a latching relay can be employed ratherthan a normally open single pole switching relay. It should beunderstood that the present disclosure should not be limited to theparticular exemplary embodiments of a processing device 108 and feedbackcircuit 110, and that and modifications such as relay type may be madewithout departing from the scope of the claims. Different types or formsof processing devices capable of controlling the operation the requiredlogic operations may be employed. For example, the processing device maybe a microprocessor that is configured to send command signals forselectively switching the relay contact.

Furthermore, different types of interface may receive the informationcommunicated by the processing device. The interface may be any devicecapable of receiving and/or responding to the communication from theprocessing device. For example, the interface may be an onsitediagnostic reporting device, a hand-held “palm” type device, or agateway for a remote network. The processing device could alsocommunicate information to a display device integrated into the relaycontroller, such as an LED (light emitting diode) or an LCD (liquidcrystal display) for visually communicating fault information. Variousother types of interfaces can be employed depending on the applicationof the relay controller and the information included in the servicerequirement.

In another aspect of the present disclosure, various methods forcontrolling operation of a relay controller are provided. In someembodiments, the method includes monitoring an expected state of therelay contacts and an actual state of the relay contacts, detecting afault condition in the contacts, and pulsing the relay until the faultcondition is overcome. The method may further include communicating thefault condition and/or the pulse characteristics corresponding to thefault condition. In other embodiments of a method, the relay may beswitched in a manner that reduces the probability of occurrence of acontact fault condition.

One embodiment of a method for controlling operation of a relaycontroller is shown in FIG. 2. The relay controller method begins atstep 202 by applying a switch signal to the relay to switch the contactsto a desired state (open or closed contacts). At step 204, the methodcompares an expected state of the relay contacts to the actual state ofthe relay contacts. If no disparity exists between the actual state ofthe relay contacts and the expected state of the relay contacts, themethod proceeds to step 208. If a disparity is detected at step 204, themethod communicates information relating to the fault condition, andproceeds to step 202 to repeat the signal for switching the relaycontacts. The method may be continued or repeated until the expectedstate of the relay contacts is the same as the actual state of the relaycontacts.

A second embodiment of a method for controlling operation of a relaycontroller is generally referenced at 300 as shown in FIG. 3. The methodbegins by applying a switch signal to the relay at step 302, and thencompares the expected state of the relay contacts to an actual state ofthe relay contacts at step 304. If no disparity exists between theactual state of the relay contacts and the expected state of the relaycontacts, the method proceeds to 318 (the relay try counter is at zeroat step 316 if contacts are in expected state). If a disparity isdetected at step 304, the method indicates or communicates the faultcondition at step 306. At step 310, the method also increments thenumber of tries, or times that the relay is signaled or pulsed to switchthe relay to a desired state. At step 314, a refresh interval is appliedbefore returning to step 302 to repeat the signal for switching therelay contacts. The method determines whether the relay pulse counterhas reached a predetermined maximum at step 308. If the predeterminedmaximum has not been reached, the relay pulse counter is incremented byone (step 310), and the method is repeated. If the predetermined maximumis reached at step 308, a service requirement or communication signal isissued at step 312. The method is followed until no disparity existsbetween the actual state of the relay contacts and the expected state ofthe relay contacts, or the predetermined maximum has been reached atstep 308.

For purposes of illustration only, the method 300 may the controloperation of a relay controller as described in the following exemplaryscenario. A fault contact condition first occurs after 100,000 switchesor cycles of the relay, and requires three pulses of the relay toovercome the condition. A second fault contact condition occurs at120,000 cycles, and requires four pulses of the relay to overcome. Athird fault contact condition occurs at 129,000 cycles, and requiresfive pulses to overcome. For each of these fault conditions, theprocessing device has stored the number of cycles or switches the relayhas accumulated at the time of the fault condition, and the number ofpulses requires to overcome the fault condition and restore the relay toexpected operation. After a preset number of intermittent fault contactconditions (such as the three above), the processing device may predicta subsequent failure at 141,000 switches. The processing device maycommunicate a service requirement to an interface or display device thatincludes the predicted failure. A response to the service requirementcan entail a technician ordering a replacement relay controller, orreplacing the relay within a minimum time frame. This progression hasbeen purely exemplary, and a different number of switches, fault contactconditions, and pulses may be stored and/or analyzed in various mannersfor predicting a fault or failure condition of the relay to becommunicated to provide notice of the predicted failure.

In another aspect of the present disclosure, various methods forcontrolling switching of a relay are provided. The life expectancy andfailure of a relay may be related to the manner of operating andswitching the relay. Thus, operating the relay in a specific manner canextend the life of the relay. For example, in applications with ACsources, the voltage applied to the relay varies between a positivevoltage and negative voltage, and closing the contacts at a point intime where a potential difference (voltage potential) between the twocontacts can lead to a sparking/arcing between the contacts just beforeclosure. This sparking/arcing can accelerate the degradation of therelay contacts, resulting in a shorter relay life. Where one relaycontact is connected to one branch of a voltage source that transitionsbetween positive voltage and negative voltage, and another relay contactcontrols a load connected to another branch of the voltage source thattransitions between positive voltage and negative voltage, the changingvoltage in both branches of the voltage source create situations inwhich the differential voltage potential between the contacts is zero(eg.—when one leg of a 208 volt Y-configuration with ground is at apositive voltage value and another leg of 208 volt three phase powersource is at the same positive voltage value).

As seen in FIGS. 4A and 4B, the voltage source is an AC source, similarto a sine wave. FIG. 4A illustrates a voltage 400 on one relay contactand a common voltage 402 on another relay contact. A ground reference404 is also shown. A contact closure occurs at line 406 when there is avoltage potential or difference between voltage waveform 400 and voltagewaveform 402. At line 406, the voltage potential between the contacts(difference between the positive voltage value of 400 and negativevoltage value of 402) generally can lead to sparking/arcing between therelay contacts. Alternately as shown in FIG. 4B, a contact closureoccurs at line 408 when the difference between the voltage value inwaveform 400 and the voltage value in waveform 402 are at a minimum(both waveforms are at about the same value). By closing at or near thecrossing point of the waveforms where the difference or voltagepotential between the waveforms is minimal, the contacts can be closedwithout risk of sparking/arcing. The prevention of sparking/arcingbetween the contacts inhibits the accelerated degradation of the relay.

A third embodiment of a method for controlling the operation of a relaycontroller is generally referenced at 500 as shown in FIG. 5. The methodis adapted to control switching of a relay to close the relay contactsconnected to a power source at a minimum voltage potential, or near thecrossing of the voltage waveforms. The method comprises an offsetsequence 500 that includes monitoring the contact closure of the relaywith respect to the crossing of the waveforms of the power source, andadjusting the time offset to minimize the time difference between thecontact closure and the crossing of the waveforms. The time offset is avariable time value that is tuned to ensure that the closure of thecontacts and the waveform-crossing coincide. The method also includesutilizing the time value or offset in commanding a closing of thecontacts of the relay. The time value for commanding a closing of thecontacts of the relay allows the contact closure to coincide with thewaveform-crossing of the power source, essentially implementing the timeoffset. The method may adjust the offset time value of the contactclosure by a value in the range of 20 to 150 milliseconds. The timeoffset achieved by the controller offset sequence 500 may be tailored tothe specific relay embodiment, and it should be understood that variouscontroller logics can be employed to adjustor offset the contact closureof a relay based on requirements of other implementations of theinvention.

Referring to FIG. 6, two waveforms of a 208 AC voltage source used in aY-configuration with respect to ground are shown. The voltage source isan AC source, having waveforms similar to a sine wave. One voltagewaveform 600 is electrically applied to one relay contact and anothervoltage waveform 602 is applied to a load in connection with anotherrelay contact. A ground reference 604 is also shown. A contact closureoccurs at point 608 when the voltage waveforms 600 and 602 are at acrossing point. At points other that 608, the voltage potential betweenthe contacts (difference between the voltage value of 600 and voltagevalue of 602) generally can lead to sparking/arcing between the relaycontacts. A contact closure occurring at crossing-point 608 where thedifference between the voltages in waveform 600 and 602 are at a minimum(both waveforms are at about the same value). It should be noted thatsuch waveform crossing is not the same as “zero-crossing”, and that asignificant voltage potential exists between the contacts when eitherwaveform 600 or 602 crosses zero volts. By closing at or near thecrossing point of the waveforms where the difference or voltagepotential between the waveforms is minimal, the contacts can be closedwithout risk of sparking/arcing. The prevention of sparking/arcingbetween the contacts inhibits the accelerated degradation of the relay.

A second embodiment of a relay controller is illustrated in FIG. 7, andis generally referenced by numeral 700. The relay controller 700includes a relay 702, a processing device 704, and a feedback circuit706. The feedback circuit is adapted to allow the processing device todetect the actual state of the contact and allow the processing deviceto detect the waveform-crossing of a power source 708. As shown in FIG.7, a block representation of a climate control system 710 includes therelay controller 700. It should be understood that a climate controlsystem is only one implementation of the invention, and various otherimplementations exist for relay controllers within the scope of thisinvention.

FIG. 8 is a schematic diagram of a feedback circuit 1000 that may beemployed in the second embodiment of a relay controller 700 above. Thefeedback circuit 1000 includes several resistors and four dualoperational amplifiers 1006, 1010, 1014, and 1022 that provide inputs toa microprocessor 1028, which controls a relay 1030 for switching linevoltage to a motor 1040. When an AC power source is connected to inputpins 1002 and 1004, operation amplifier 1006 outputs an AC signal to amicroprocessor input pin 1008, which monitors the voltage value. Anoperational amplifier 1010 outputs a direct current (DC) square wave tomicroprocessor input pin 1012. The rising and falling edges of the DCsquare wave (pin 1012) coincide with the pin 1008 waveform intersectinganother waveform of the power source (i.e. zero-voltage potentialbetween the AC waveforms). Thus, transitions in the DC square wave inputpin 1012 denote the waveform crossings of the AC power waveformssupplied to pins 1002 and 1004.

The voltage across the motor 1040, which is switched by a relay 1030that is controlled by the microprocessor 1028, is monitored by anoperational amplifier 1014. Based on the signal at input pin 1012, themicroprocessor switches the relay 1030 and calculates a time offset withrespect to the waveform-crossing point and the closing of the relaycontacts. When the relay contacts close to cause the voltage across themotor 1040 to be sensed by operational amplifier 1014, a direct currentsquare wave is output from operational amplifier 1022 to themicroprocessor input pin 1016. The microprocessor is adapted tocalculate the difference (if any) in time between the relay contactclosure from input pin 1016 and the waveform-crossing from input pin1012. That difference is added or subtracted (as appropriate) to adjustthe offset time, for subsequently switching the relay 1030 such that therelay contacts close at or near the waveform cross point where thevoltage potential between the waveforms is minimized, as described inFIGS. 4A, 4B, and FIG. 6. This feedback circuit 1000 and its operationshould be understood to be one preferred embodiment of the presentinvention. It should be noted that the feedback circuit, microprocessor1028 and relay 1030 may be integrated into a single relay controllerdevice. Other circuits and different components can be employed tocreate a feedback circuit within the scope of the invention.

Referring to FIG. 9, a graph illustrates a ninth embodiment of a methodfor operating a relay controller. The processing device commands theswitching of the relay contacts as required for the application. Themethod comprises detecting a first fault weld condition by a disparitybetween an expected position of the relay and the actual position of therelay, and storing the number of switches (or cycles) the relay made asof the contact weld fault condition. The method pulses the relay anumber of times until the weld condition is overcome, and stores thenumber of pulses required to overcome the welded contact failurecondition. The method then calls for detecting a second weld conditionand storing the number of relay switches when the weld conditionoccurred, subsequently pulsing the relay a number of times until thesecond weld condition is overcome, and stores the number of pulsesrequired to overcome the second weld condition. The method also providesfor determining a predicted failure of the relay contacts based on thenumber of fault conditions relative to the number of relay switchingoccurrences, the number of pulses required to overcome the relay weldcondition, or both. For example, empirical testing of a specific relaytype may show that after 6 or more pulses, the welded relay contactswill not likely be able to be corrected. The method may use numericalanalysis methods, such as linear or geometric progressions, to estimatewhen the relay will fail based on the progression of the number ofpulses required to correct the weld fault, or the progression of thenumber of weld fault conditions relative to the number of relayswitching cycles, or a combination of both. The graph in FIG. 9illustrates this method by way of example of a hypothetical series ofrelay contact weld fault conditions. A first contact weld faultcondition occurring at 159,000 cycles requiring 2 pulses to overcome theweld is shown at 1110. A second contact weld fault condition occurringat 259,000 cycles requiring 2 pulses to overcome the second weld isshown at 1120. A third contact weld fault condition occurring at 339,000cycles requiring 3 pulses to overcome the third weld is shown at 1130. Afourth contact weld fault condition occurring at 379,000 cyclesrequiring 4 pulses to overcome the fourth weld is shown at 1140. A fifthcontact weld fault condition occurring at 399,000 cycles requiring 5pulses to overcome the fifth weld is shown at 1150. Based on theprogression of pulses, the method could predict that the next weldcondition could require more than 5 pulses, in which case the relaycontact weld condition could likely become permanent. Likewise, based onthe progression of the number of fault conditions relative to the numberof cycles (eg. 80,000 cycles after 3^(rd) fault, 40,000 cycles after4^(th) fault, 20,000 cycles after the 5^(th) fault), the method couldpredict that the next weld condition could occur in approximately 10,000cycles at 1160 (at 419,000 cycles). Each of the above predicted failurecriteria may be implemented individually or in combination with eachother to provide for communication of a service report that includes apredicted failure estimation. It should be noted that various algorithmsmay be employed to weight the weld contact failure condition data, or tocombine the progression of the data to compile the data into anestimated predicted welded contact failure event of the relay, forcommunicating in a service report.

When describing elements or features of the present invention orembodiments thereof, the articles “a”, “an”, “the” and “said” areintended to mean there are one or more of such elements or features. Theterms “comprising”, “including” and “having” are intended to beinclusive and mean there may be additional elements or features beyondthose specifically described.

Those skilled in the art will recognize that various changes can be madeto the exemplary embodiments and implementations described above withoutdeparting from the scope of the present invention. Accordingly, allmatter contained in the above description or shown in the accompanyingdrawings should be interpreted as illustrative and not in a limitingsense.

1. A controller for establishing electrical connection between a motorand an alternating current power source having a firstalternating-current voltage waveform and a second alternating-currentvoltage waveform, the controller comprising: a relay having a firstrelay contact and a second relay contact adapted to close to establishan electrical connection between the first and second voltage waveformsand a motor; a first electrical circuit having input connections adaptedfor connection to the first and second voltage waveforms, the firstelectrical circuit being configured to provide a signal denoting a timewhen each of the first and second waveforms are each at a voltage valueother than zero volts, and the difference in voltage potential betweenthe first alternating-current voltage waveform and the secondalternating-current voltage waveform is at or near a minimum value, atwhich time the relay is initially switched to initiate closure of thefirst and second relay contacts; a second electrical circuit havinginput connections with the first and second relay contacts formonitoring the relay contact position, wherein when the relay first andsecond contacts are closed, the second electrical circuit is configuredto provide a signal denoting a time when the relay contacts have closedand opened; a microprocessor configured to switch said relay causing theopening and closing of first and second relay contacts, wherein themicroprocessor is configured to monitor the first and second signals todetermine a difference in time between when said relay is initiallyswitched where the difference in voltage potential is at or near aminimum value, and when said first and second relay contacts actuallyclose, where the microprocessor utilizes said time difference value indetermining a switch initiation time relative to a time where thedifference in voltage potential is at or near a minimum value, such thatthe first and second relay contacts close when the voltage potentialbetween the first and second alternating-current voltage waveforms is ator near a minimum value, to thereby reduce the potential for arcing. 2.The controller of claim 1, wherein the microprocessor is configured toprovide a voltage pulse to the relay to initiate switching of the relayto cause the contacts to close.
 3. The controller of claim 2 wherein themicroprocessor is further configured to initiate switching of the relayto cause the contacts to move to an open position.
 4. The controller ofclaim 3 wherein the microprocessor is configured to monitor the secondsignal to detect a disparity between the expected position of therelay's contacts and an actual closed position of the relay's contacts,indicative of a welded relay contact condition.
 5. The controller ofclaim 4 wherein the microprocessor is operable to pulse the relay with avoltage signal to overcome the fault contact condition.
 6. The relaycontroller of claim 5 wherein the processing device is adapted to storepulse characteristics including at least the number of pulses necessaryto overcome the fault contact condition.
 7. The controller of claim 4wherein the first and second electrical circuits are first and secondoperational amplifiers.
 8. The controller of claim 7 wherein the firstelectrical circuit is configured to determine the time when saiddifference in voltage potential between the first alternating-currentvoltage waveform having a non-zero voltage value and the secondalternating-current voltage waveform having a non-zero voltage value isat or near a minimum value.
 9. A controller for establishing electricalconnection between a motor and an alternating current power sourcehaving a first alternating-current voltage waveform and a secondalternating-current voltage waveform, the controller comprising: a relayhaving a first relay contact and a second relay contact adapted to closeto establish an electrical connection between the first and secondvoltage waveforms and a motor; a first electrical circuit having inputconnections adapted for connection to the first and second voltagewaveforms, the first electrical circuit being configured to provide asignal denoting a time when a difference in voltage potential, betweenthe first alternating-current voltage waveform having a non-zero voltagevalue and the second alternating-current voltage waveform having anon-zero voltage value, is at or near a minimum value, at which time therelay is initially switched to initiate closure of the first and secondrelay contacts; a second electrical circuit having input connectionswith the first and second relay contacts for monitoring the relaycontact position, wherein when the relay first and second contacts areclosed, the second electrical circuit is configured to provide a signaldenoting a time when the relay contacts have closed and opened; amicroprocessor configured to switch said relay causing the opening andclosing of first and second relay contacts, wherein the microprocessoris configured to monitor the first and second signals to determine adifference in time between when said relay is initially switched wherethe difference in voltage potential is at or near a minimum value, andwhen said first and second relay contacts actually close, where themicroprocessor utilizes said time difference value in determining aswitch initiation time relative to a time where the difference involtage potential is at or near a minimum value, such that the first andsecond relay contacts close when the voltage potential between the firstand second alternating-current voltage waveforms is at or near a minimumvalue, to thereby reduce the potential for arcing.
 10. The controller ofclaim 9 wherein the microprocessor is configured to provide a voltagepulse to the relay to initiate switching of the relay to cause thecontacts to close.
 11. The controller of claim 10 wherein themicroprocessor is further configured to initiate switching of the relayto cause the contacts to move to an open position.
 12. The controller ofclaim 11 wherein the microprocessor is configured to monitor the secondsignal to detect a disparity between the expected position of therelay's contacts and an actual closed position of the relay's contacts,indicative of a welded relay contact condition.
 13. The controller ofclaim 12 wherein the microprocessor is operable to pulse the relay witha voltage signal to overcome the fault contact condition.
 14. The relaycontroller of claim 13 wherein the processing device is adapted to storepulse characteristics including at least the number of pulses necessaryto overcome the fault contact condition.
 15. The controller of claim 12wherein the first and second electrical circuits are first and secondoperational amplifier circuits.
 16. A controller for establishingelectrical connection between a motor and an alternating current powersource having a first alternating-current voltage waveform and a secondalternating-current voltage waveform, the controller comprising: a relayhaving a first relay contact and a second relay contact adapted to closeto establish an electrical connection between the first and secondvoltage waveforms and a motor; a first operative-amplifier circuithaving input connections adapted for connection to the first and secondvoltage waveforms, the first operative-amplifier circuit beingconfigured to provide a signal denoting a time when each of the firstand second waveforms are each at a voltage value other than zero volts,and a difference in voltage potential between the firstalternating-current voltage waveform having a non-zero voltage value,and the second alternating-current voltage waveform having a non-zerovoltage value, is at or near a minimum value, at which time the relay isinitially switched to initiate closure of the first and second relaycontacts; a second operative-amplifier circuit having input connectionswith the first and second relay contacts for monitoring the relaycontact position, wherein when the relay first and second contacts areclosed, the second operative-amplifier circuit is configured to providea signal denoting a time when the relay contacts have closed and opened;a microprocessor configured to switch said relay causing the opening andclosing of first and second relay contacts, wherein the microprocessoris configured to monitor the first and second signals to determine adifference in time between when said relay is initially switched wherethe difference in voltage potential is at or near a minimum value, andwhen said first and second relay contacts actually close, where themicroprocessor utilizes said time difference value in determining aswitch initiation time relative to a time where the difference involtage potential is at or near a minimum value, such that the first andsecond relay contacts close when the voltage potential between the firstand second alternating-current voltage waveforms is at or near a minimumvalue, to thereby reduce the potential for arcing.
 17. The controller ofclaim 16 wherein the microprocessor is configured to provide a voltagepulse to the relay to initiate switching of the relay to cause thecontacts to close.
 18. The controller of claim 17 wherein themicroprocessor is further configured to initiate switching of the relayto cause the contacts to move to an open position.
 19. The controller ofclaim 18 wherein the microprocessor is configured to monitor the secondsignal to detect a disparity between the expected position of therelay's contacts and an actual closed position of the relay's contacts,indicative of a welded relay contact condition.
 20. The controller ofclaim 19 wherein the microprocessor is operable to pulse the relay witha voltage signal to overcome the fault contact condition.